In recent years, so-called “hybrid vehicles” have become increasingly popular. These vehicles typically supplement the power produced by a more-conventional internal combustion engine with power generated by one or more electric motors, thereby dramatically reducing fuel consumption without significant effects upon the driving experience.
Despite the success of hybrid vehicles, however, it is always desirable to provide increasing levels of power from the electric motor(s) present on the vehicle. Typically, increased power can be obtained by providing additional motors, larger motors, larger magnet structures in the existing motors, and/or by boosting the electrical current driven through the armature coils of the motor during operation. More particularly, inverter circuits have been designed to increase the power provided within the electric motor system. A conventional six-switch, three-leg inverter topology, for example, can increase the power of a system that includes one or more three-phase motors. Even this arrangement, however, can be limited in its ability to increase available power and/or to decrease the current rating of the inverter. In particular, thermal constraints at low fundamental operating frequencies can make it difficult for conventional inverter circuits to produce desired levels of current, thereby resulting in decreased motor torque at low speeds.
Accordingly, it is desirable to provide an improved inverter scheme for obtaining increased power from a multi-motor system without adding complexity to the system or increasing the motor size. In particular, it is desirable to address temperature effects on inverter operation to produce additional motor torque at low fundamental frequencies. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.